Roddam AW et al. (2008) Insulin-like growth factors, their binding proteins, and prostate cancer risk: analysis of individual patient data from 12 prospective studies. Ann Intern Med 149: 461–471

Some studies have indicated that levels of circulating insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) correlate with the risk of developing prostate cancer, whereas other studies have shown no such relationship. Roddam et al. have now found that high circulating levels of IGF-I are associated with a moderately raised risk of developing prostate cancer.

The authors searched PubMed, Web of Science and CancerLit databases for all studies that provided prospectively collected data on circulating concentrations of IGFs or IGFBPs and prostate cancer risk. The authors of these studies were invited to submit individual participant data to a central data set.

In the 3,299 patients with prostate cancer and 4,436 control individuals studied, the risk of prostate cancer increased as circulating concentrations of IGF-I increased (odds ratio for the highest versus lowest quintile 1.38; P <0.001 for trend). Elevated IGF-I concentrations were more strongly associated with low-grade disease than high-grade disease. Raised levels of IGFBP3 were also associated with increased prostate-cancer risk; however, this effect was secondary to the correlation between IGFBP3 and IGF-I levels. Neither IGF-II nor IGFBP-2 concentrations were associated with prostate-cancer risk.

The relationship between IGF-I and prostate-cancer risk could be related to the mitogenic and antiapoptotic effects of this growth factor. The authors propose that modification of circulating IGF-I levels through dietary and lifestyle changes might reduce the risk of prostate cancer.